A man bought two books for RS 1040. He sold one at a loss of 15% and other at a profit of 36% then he found that each book was sold for the same price. Find the cost price of each book.

You just purchased two coins at a price of $670 each. because one of the coins is more collectible, you believe that its value will increase at a rate of 7.1 percent per year, while you believe the second coin will only increase at 6.5 percent per year. if you are correct, how much more will the first coin be worth in 15 years?